MS-DOS is old, very old by computer standards. It is not compatible with most programs and applications now. It won't run right or at all on most newer computers, printers or anything else.
If you want to use dos you should have an older computer like 1993 and older. Dos will run older programs and software like 10+ years old but it will not run any windows program even old windows 3.1 programs unless it is installed. A few of those older programs were neat or were useful but most of of it is no where near as good as the new stuff now which is windows compatible.
Dos can also be useful for anyone who is into basic programing.